Mouse CD11bhighLung Dendritic Cells Have More Potent Capability to Induce IgA than CD103+Lung Dendritic CellsIn Vitro

Lung dendritic cells (LDCs) are primary antigen-presenting cells that develop IgA-producing plasma cells in the lung through class switch recombination (CSR) in naive B cells. Recently, the major LDC subsets were found to comprise CD103(-)CD11b(high) LDCs (CD11b(high) LDCs) and CD103(+)CD11b(low or negative) LDCs (CD103(+) LDCs), but their abilities to induce IgA production have not been defined. Under T cell-dependent (T-D) and T cell-independent (T-ID) conditions, we compared the abilities of these two LDC populations to induce IgA. CD11b(high) or CD103(+) LDCs obtained from BALB/c mice were cocultured with naive IgD(+) B cells in the presence of LPS, with or without anti-CD40 monoclonal antibody (mAb) (i.e., T-D and T-ID coculture conditions, respectively). Under both T-D and T-ID conditions, CD11b(high) LDCs induced significantly greater amounts of IgA production, together with a significantly higher mRNA expression of activation-induced cytidine deaminase, than did CD103(+) LDCs. However, the protein expression of a proliferation-inducing ligand, B cell-activating factor of the tumor necrosis family, or retinaldehyde dehydrogenase-1 did not differ between the two LDC subsets. CD11b(high) LDCs displayed a significantly greater capacity to secrete IL-6 and IL-10 in response to LPS, with or without anti-CD40 mAb. Moreover, the IgA production induced by CD11b(high) LDCs in T-D coculture was attenuated by neutralizing both IL-6 and IL-10. These findings suggest that, of the two major LDCs, CD11b(high) LDCs more efficiently induce IgA than do CD103(+) LDCs, possibly through their potent capacity to produce IgA-inducing cytokines.